The invention relates to a machine tool, in particular milling center, with a frame, a carrier for tools and/or workpieces, a coupler mechanism guide starting at the frame in order for guiding the carrier, and a drive device starting from the frame for moving and fixing the carrier.
Machine tools with coupler mechanism guided carriers are more flexible, lighter and more dynamic as compared to those machine tools with guide (rail) led carriers, which is based on the one hand on the elimination of the guides extending over the complete course including their foundations and their coverings and strippers and on the other hand on the thereby substantially smaller working surface of guided cards for chips and process auxiliary agents. A known device for the working and/or mounting of tool pieces according to the printed patent document EP 0,812,652 A1 exhibits a coupler mechanism guide, which allows a planar motion to a carrier adjustable by two linear drives. Motions perpendicular to this plane are realized by center sleeve like or quill like formation of the carrier and/or by separate table motions. Both is again connected with the disadvantages of guide (rail) led carriers, wherein here the guides of the table and/or the center sleeve as well as the associated coverings and strippers are limiting the obtainable speeds and accelerations.
In addition machine tools are known wherein the carrier is guided, moved and fixed by six in each case numerically controlled NC-linear actuators in space. The dispensing with coupler mechanism guides increases the control expenditure, the costs and the space requirements.
It is an object of the present invention to furnish a machine tool of the kind recited, wherein the machine tool is lighter upon realization as of comparable courses and allows higher speeds and accelerations.
This object is accomplished according to the present invention in that the coupler mechanism guide includes first means, in order to guide the carrier in the first plane covering the surface, and includes second means in order to swivel the carrier in a second plane intersecting the first plane, wherein the drive device exhibits third means in order to move and, to fix in position the aligned guided in space. By having each point describable by a Cartesian coordinate triple x, y, z reachable by a coupler mechanism guide movable surface covering in the first plane and swivelable in the second plane, wherein the coupler mechanism guide binds the three degrees of freedom of the rotations around the Cartesian axes x, y, z, which is reachable and is controllable by a drive device starting at the frame, which drive device binds the three degrees of freedom of the displacements along the Cartesian axes x, y, z. There is further required neither a center sleeve like formation of the carrier supporting the tool and/or the work piece nor a corresponding motion to the carrier of a device supporting the workpiece or, respectively, the tool, for example a table or, respectively, a tool holder.
Here the carrier is guidable in the first plane while maintaining the spatial alignment defined by an alignment axis, wherein the first plane comprises preferably the alignment axis. The carrier is preferably supported by the first means, wherein the first means are preferably swingable in the second plane.
The first means comprise at least one parallelogram like four bar chain, preferably at least two to each other connected parallelogram like four bar chains, wherein the first four bar chain starting at the frame is connected to the second four bar chain leading to the carrier and wherein the hinge axes disposed remote from the frame of the two first members of the first four bar chain having equal length and starting from the frame and the hinge axes disposed remote from the carrier of the two second members of equal length leading to the carrier are disposed preferably in a common connecting rod closing one of the four bar chains. This connecting rod or coupler exhibits the three hinge axes, wherein a first member is supported around the first hinge axis, wherein both another first member as well as a second member are supported around the second hinge axis of the coupler, and wherein another second member is supported around the third hinge axis of the coupler. Instead it is also possible to furnish the coupler only with tool hinge axes, wherein both a first member and also a second member are supported around each of the two hinge axes. In addition to, the coupler can also be disposed between the members starting from the frame and/or the members leading to the carrier such that the hinge axes of the coupler exhibit the same distance in each case from the frame bound hinge axes or, respectively, the carrier bound hinge axes. Finally, it is provided to furnish a first member and a second member with a larger cross-section for receiving both pull forces and compression forces as well as bending forces and torsional forces as compared to the in each case other first member and second member, which received only pull forces and compression forces. The second means allow the swivelability of the first means in the second plane. The second means carrying the first means and are swivelable around a swivel axis disposed at the frame, which swivel axis is aligned preferably parallel to the alignment axis. The second means comprise in particular a swivel device or, respectively a swivel body, wherein the swivel body can be swiveled around this swivel axis and carries the first means. The second means can however also be formed as a support of the first means such that for example the four bar chain is swivelable both in the first plane as well as also in the second plane by way of ball and socket joints or universal cardan joints.
The third means exhibit actuators (preferably at least three), wherein the actuators on the one hand are hinged at the frame and on the other hand are hinged at the carrier or at the first means, wherein the hinge distances can be changed for each actuator. They comprise preferably at least three linear actuators changeable in length relative to the frame, wherein the linear actuators are hinged with their one end at frame positions disposed at a distance from each other and are hinged with their other end at the carrier. The joining is performed by a cardan joint and/or by a ball and socket joint. The hinge points are disposed staggered by in each case 120 degrees as seen in the direction of the alignment axis. The actuators or, respectively, the linear actuators enclose an angle of 45 degrees with the alignment axis in a central work point of the carrier and the actuators or, respectively, linear actuators enclose an angle of 90 degrees with the two hinge axes of the cardan joint. The linear actuators preferably comprise in each case a rotary drivable nut and an axially shiftable threaded spindle fixed against rotation, alternatively the linear actuators can also be formed as linear direct drives, as gear rackxe2x80x94gear pinion drives, working cylinders and the like. However, it is also possible to employ actuators which change their hinge distances in a different way, for example by opening or closing tongs like connected arms.
The carrier is preferably formed as a head stock or a drill head, wherein the work spindle receiving tools and/or workpieces is supported in the head stock, wherein the rotary angle position of the work spindle can be corrected, for example by way of software, and wherein the rotary axis of the work spindle preferably coincides with the alignment axis. The carrier can also support however fixed positioned tools and/or workpieces. If the carrier supports a tool, wherein the workpiece received on a work piece table is millable with the tool, then a spatially fixed first casing can arch around the first means and around the second means and around the third means and a second casing foldable away can arch over the work piece table, wherein the first casing and the second casing form together a cockpit like overall casing, wherein at least the second casing is transparent. A weight balancing device can be disposed between two members of the four bar chains, wherein the weight balancing device is preferably formed as a compression spring. An energy feed chain is led in parallel to the four bar chains.